If you look at CR from last year and early this year, there was a fair bit of buzz that Canon would update the 100-400mm, since it's a hugely popular lens that was released in 1998 and needed better IS and weather sealing. But then, if you look at POTN from 2004, there was a lot of buzz that Canon would be updating the 100-400mm since it was a hugely popular lens that was released in 1998 and needed better IS and weather sealing. Get the idea?
What I take away from that is they looked at their different buying demographics, and seem to have decided that hobbyists who didn't mind the 100-400's lower-tier (compared to die-hard pros who can lug around primes) sharpness and features, but needed that focal length at that price point, would jump at a new, slightly shorter focal length (shorter range as well), lighter, less expensive lens to mate with the APS-C sensors that have come out since then. The fact that former film shooters who started saying "gee, my 100-400 is just too dang long on these digital bodies" weren't a major demographic moving in droves to 70-300s before doesn't seem to have been a factor. Apparently Canon judged 400mm would have added too much weight, and / or it would have been less critical than 300mm (which they noted appears like a 480mm lens image anyway).
The story recently has been of the retooling of product lines. Thus the 60D is not a 50D successor (frankly, a 50D successor with just upgraded main points, but no new features, would have been thrashed fairly soundly, as even the 60D was - its downgrades are few and mostly minor).
I see the big picture as there being a big segment of the market - the lower-cost professional camera around $2500 - being served by a two year old camera in a segment that moves fairly quickly. As we've all said before - yes it's full-frame, but it also doesn't have the most professional feature set. Autofocus is a big example. The 5D Mark II's AF system was apparently more or less kept over from the original 5D, so it's quite old. The metering is pre-iFCL, so less accurate than the 7D in all likelihood.
The recent trend of prices seems to be up, though there's no reason to suspect this is an iron rule. Nikon and Sony are still out there, and other players are joining up, so Canon cannot unilaterally jack up prices unless their cameras are really far ahead of the competition on special features (thankfully the articulating screen wasn't considered one, as the 60D is cheaper in 2010 dollars than the 50D was in 2008 dollars). The 60D appears to be the shaky pillar of Canon's pricing, as all the D7000 talk has shown, so it'll be interesting to see which way the pricing of the next model goes.
The 5D Mark II is also in a totally different segment, however. With the introduction of the 60D and the 7D before it, there's a good reason to suspect they may try to move the 5D's placement one way or another. (Probably up, if anything.) But then the full-frame aspect makes it unique compared to the others, still. The 7D was for people who need 5D-like features in a APS-C-priced body, and for Canon to sell a premium APS-C camera (milk those crop sensors, it only makes sense). That probably takes away some buyers who previously would have looked only at the 5D Mark II. The 5D Mark II will have to re-justify its price point, aside from the full-frame-at-any-cost crowd (which I would enjoy joining).
It's also kind of interesting to note that there isn't any cheap 1.3x crop camera. I suspect they decided the 1.3x sensors weren't so much cheaper than full frame to warrant more production of them, but the crop factor usually ought to help out one of the target audiences, sports and news shooters.